1. Field of the Invention
This invention relates, generally, to ergonomics improvements for a mono-block frame used in bicycles and the like. More particularly, it relates to a hollow mono-block frame formed entirely of an injection-molded thermoplastic polymer.
2. Description of the Prior Art
The mechanical safety and physical condition of the parts that make up a bicycle such as the frame, the brake system, the handlebar and the like, are important because they enable the cyclist to steer, brake, and to otherwise be safe during the ride. Accidents caused by a mechanical failure or breakage of a part can cause serious injury to the cyclist.
The frame of a conventional bicycle includes a set of extruded tubes that are typically manufactured with carbon steel, chrome-molybdenum and aluminum. Such frames are cut, bent and welded in accordance with a predetermined design. The resulting structure is therefore rigid, inflexible, and not well-adapted to absorbing impacts.
The assembly of such metallic extruded tubes is carried out in a standardized pattern and the parts are fastened to one another by local welded spots in a welding operation performed either manually or by robots.
Remaining parts such as the forks, the seat and the like are installed and fastened by bolts or other fastening means to their respective mounts after the frame is welded.
However, such welded spots may fail; the breaks in a conventional bicycle's frame are often found in the welded spots. The most vulnerable points are those located between the central, longitudinally disposed bar and the tube that engages the handlebar. Breakage also occurs between the tube that supports the seat and the central, longitudinally disposed bar. These breakages occur primarily due to the stress placed upon the bicycle by the weight of the cyclist and by the pushing, pulling, jerking, pounding, and twisting of the bicycle parts as the cyclist exerts maximum effort.
Conventional metallic frames are also quite heavy. Manufacturers of bicycles and the like are continually trying to develop damage-resistant yet light-in-weight materials.
Early bicycle frames were made of steel. Aluminum was later employed, followed by chrome and chrome libidinum. These materials are gradually being replaced by aluminum alloys having technological innovations that offer greater resistance to damage than pure aluminum. However, metallic frames are somewhat inconvenient since they are prone to bending and breaking when severe forces are applied to them.
Carbon fiber is another raw material presently used for manufacturing the frames of bicycles. It is light-in-weight and damage-resistant. It absorb impacts better than metallic materials and therefore allows the bicycle to ride more smoothly and regularly across the ground with shocks of reduced intensity. Although carbon fiber is expensive, it outlasts metallic frames under the normal wear and tear of daily use and does not bend when subjected to severe impacts.
There is a need for a bicycle construction that is light-in-weight, built of durable, substantially non-breakable materials, that can be assembled quickly, that is extra strong in places where conventional bicycles most often break, and that is safe and comfortable to ride.
However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the art how the identified needs could be fulfilled.